1. Field of the Invention
The present invention relates to a fire hydrant, and more particularly, to a three-way wet barrel fire hydrant having an improved barrel design.
2. Background and Related Art
A "wet barrel" fire hydrant is a type of fire hydrant which retains water in the hydrant barrel during non-use. Wet barrel fire hydrants are employed in temperate climates of the country, such as Hawaii and Southern California, because in climates where the air temperature drops below freezing, the water would freeze within the barrel and render the hydrant inoperative.
A "three-way" wet barrel fire hydrant has three nozzles: one large pumper nozzle and two smaller hose nozzles. The pumper nozzle is adapted to receive a hose connected to a pumper fire truck. Both hose nozzles are adapted to receive hoses employed to extinguish the fire.
According to the three-way fire hydrant hose arrangement, water flows in the following path: from the hydrant pumper nozzle to the pumper truck, where the water pressure is increased; and from the pumper truck to various hose nozzles for application to the fire.
FIGS. 1(a) and 1(b) show a conventional three-way fire hydrant barrel 10 having a base opening 12, three nozzle openings--a pumper nozzle opening 14, a middle nozzle opening 16 and an upper nozzle opening 18--and three corresponding operating valve stem openings--pumper valve stem opening 15, middle valve stem opening 17 and an upper valve stem opening 19. As shown in FIG. 1(a), a cross-sectional centerline X of the corresponding middle nozzle and valve stem openings 16 and 17 and a cross-sectional centerline Y of the corresponding upper nozzle and stem openings 18 and 19 are oriented 45.degree. (or 60.degree. in another embodiment) from a cross-sectional centerline Z of the corresponding pumper nozzle and stem openings 14 and 15. Centerline Z coincides with mold parting line A, which is discussed in more detail below.
As shown in FIG. 1(b), the hydrant barrel 10 has an approximately constant diameter along the longitudinal axis. The hydrant barrel 10 has only a slight bulge at an intermediate section 11.
Three-way wet barrel fire hydrants have two primary design considerations. First, a three-way fire hydrant is preferably light weight. Second, a three-way fire hydrant must have low pressure loss. Unfortunately, the two design considerations are in conflict. Conventional three-way wet barrel fire hydrants, such as the one shown in FIGS. 1(a) and 1(b), fail to satisfy both design considerations. Under conventional designs, either a light weight fire hydrant or a low pressure loss hydrant is possible, but not both.
Conventional methods for manufacturing three-way fire hydrants employ a sand molding process followed by a casting process. During the sand molding process, a pattern 30 having an exterior shape of a three-way fire hydrant shape is pressed into molding sand 20 to form a hydrant sand mold (see FIG. 2). The pattern 30 includes a pumper valve stem projection 32, an upper valve stem projection 34, a middle nozzle projection 36 and a pumper nozzle projection 38. After the molding sand 20 hardens, the pattern 30 is withdrawn (to the left in FIG. 2) leaving a hydrant shaped sand mold.
The above described process forms one half of the mold. A similar process forms the other half of the mold. Both mold halves are joined together around a core 22. The two mold halves and the core 22 define a mold cavity 24 into which molten iron is poured to form a casting as shown in FIG. 3. The core 22 includes three core prints 26a, 26b and 26c which define the pumper nozzle, pumper valve stem and base openings, respectively. The molten metal cools in the mold cavity 24 to form the hydrant barrel. The mold parting line A shown in FIGS. 1(a) and 1(b) illustrates where the two mold halves are joined.
Conventional methods, however, have several disadvantages. A first disadvantage is illustrated in FIG. 2. When the pattern 3 is withdrawn from the molding sand 20 (to the left in FIG. 2), the upper valve stem projection 34 is pulled through the sand mold in area B and the middle nozzle projection 36 is pulled through the sand mold in area A, leaving undesired voids in the sand mold.
As a result, side cores must be constructed to replace the void areas in the sand mold. The side cores form portions of the upper valve stem opening 19 and the middle nozzle opening 16 which would not otherwise be formed since the molding sand in that area has been removed. In the conventional three-way fire hydrant shown in FIGS. 1(a) and 1(b), four side cores are employed to form each barrel 10: two side cores for the right half and two for the left half.
Since these side cores are formed by a secondary process, additional time and expense are incurred in the conventional manufacturing method.
A second disadvantage of conventional methods is an inherent problem known as "floating core". The inventors of the present invention have recognized that a significant portion of the weight of conventional three-way hydrants is due to additional wall thickness required by the casting process to compensate for the "floating core" problem. As shown in FIG. 3, core prints 26a and 26b protrude oppositely from the middle of the core 22 to shape the pumper nozzle opening and the pumper valve stem opening, respectively. A third core print 26c protrudes from the base of core 22 to from the base opening. The core prints 26a, 26b and 26c support the core 22 during the casting process. However, since the core prints 26a and 26b protrude from the middle of the core 22, an overhang portion 28 of the core 22 extends well beyond the support of core prints 26a and 26b. As a result, the overhang portion 28 may float up or down during solidification of the molten metal. Therefore, a thicker casting average wall thickness is required to maintain the minimum wall thickness required by industry standards, thereby increasing the overall weight of the hydrant.
On possible solution to the "floating core" problem is to move the core prints to the upper portion of the core to better support the overhang portion. However, such a modification under conventional methods results in higher manufacturing costs due to additional side core expense. As discussed above, four side cores are required to form portions of the openings oriented off the mold parting line A. When the core prints protrude from the middle of the core through the pumper nozzle opening and the pumper valve stem opening, side cores must be made for the middle and upper nozzle and valve stem openings. Since the middle and upper nozzle openings are the same size, as are the middle and upper valve stem openings, the same tooling set may be used to make the respective side cores.
On the other hand, if the core prints were positioned on the upper portion of the core to form the upper nozzle and valve stem openings, side cores must be made for the middle nozzle and valve stem openings and the pumper nozzle and valve stem openings, which are different sizes. Thus, additional tooling sets are required to make both sets of side cores, thereby increasing tooling costs. Therefore, conventional methods of manufacturing three-way fire hydrants have opted to reduce tooling costs, while tolerating an increased hydrant weight.
Accordingly, there is a need for a three-way wet barrel fire hydrant which is light weight and has low pressure loss, yet is economically feasible to manufacture.